If this is the proposed design, remember that you will also have the corner and the countertop to the sink, which is where much prep takes place. You might, however however, reconsider the cabinet that comes all the way to the countertop, you might find it is in your way. If you have any prep going on in front of it, you won’t be able to open the door. You could do a shorter cabinet and still use the space below for storage and for work.

Ideally you want a 42" hood over a 36" range.

I would not do that cabinet down to the counter in the corner.

Another vote to lose the glass cabinet sitting on the counter.

What is to the left of the range? Is that a tall pantry or is it a wall?

If you originally had planned for 18” on each side, is there a reason you want to go down to 15”?

You’ll have lots more space if you nix the corner cabinet - that’s your easiest prep area there. We have 12” on one side of stove and 48” on other. it’s ok because of the large space on one side, but 18” would certainly be nicer! i’d try to do 18” especially as it looks like there is a wall or cab on left side.

Having had 11”, 12”, and now 18” on one side, and 0” or the ”return” towards the sink on the other, you can handle whatever you have.

Instead, think about how you will use that space, above and below the countertop. Will you have drawer stacks on either side? Cabinets? what will you store in them? How much width do those items need? And how will you use the countertops? do you use utensil canisters for your most-used utensils? Keep salt and pepper etc there? lid holders? paper towels?

Imagine how you will use it, and think about what you have currently or in the past, and how that worked for you.

We have had a kitchen with zero-maybe an inch or two between range and sink on one side , similar to @bpath, and NO counter on other side of range. Managed with it for 20 years. I would imagine 15” would be fine honestly. If you can manage the 18” it certainly wouldn’t hurt

With 15" you will have 15" + 25" on the right side, if that cabinet does not rest on the counter and 15" + partial use of that 25" if it does. And you are a step away from the adjacent run as well. It should be fine.

Also consider the size of the base cabinets. 15" is a rather narrow base cabinet for storage. I have an 18" drawer base on the one side of my range which is pretty useful for storage, anything smaller would be far less useful unless it were a specialty cabinet like a tray cabinet or something.

Are you moving the refrigerator? I know the picture you show is a rendering, I wonder if the new refrigerator placement, while following the ice-water-stone-fire concept (and my own experience that a lot of meal prep is ice-stone-dishwasher, as in cereal and sandwiches and snacks) blocks light from the sink window? Is there a better light at the kitchen table?